As already said bitcoin is already a good investment, but i believe the op wanna to invest the btc into others ways to get more bitcoins, casino bankrolls and few altcoins might be a good investment, outside those you will have to start your project, but be sure competition is very strong at the moment.
Investing in casino bankrolls is a good choice but to make good profits from it you also be ready with good capital to invest and before investing you need to do good research about it as there are many scam sites that will disappear in future without paying you anything.